This Project has two goals: 1. To identify and characterize the single nucleotide polymorphisms (SNPs) that are[unreadable] found in the human genes which compose the p53 pathway in cells. 2. To expand and utilize the algorithm[unreadable] we have previously designed to detect the p53 responsive elements (P53 REs, the DNA[unreadable] sequences that permit a gene to be regulated by p53) and identify the genes regulated by p53 in the mouse[unreadable] and human genomes. To date we have identified over 1,300 SNPs in 82 genes in the human genome that[unreadable] function in the p53 network and we are creating a web site to share these data. We have developed[unreadable] methods to identify which SNPs have the best chance of altering the molecular, cellular and clinical[unreadable] phenotypes of the p53 pathway. We have focused upon several SNPs (the lead SNPs are in HDM-2, Perp[unreadable] and AKT), which result in an altered phenotype at the molecular (changed levels and activity), cellular (an[unreadable] altered frequency of apoptosis) and clinical (a younger age of onset of cancers and increased number of[unreadable] cancers in humans) levels of analysis. We have characterized 120 EBV-transformed lymphoblastoid cell[unreadable] lines from normal individuals for their apoptotic index (the percentage of cells that undergo apoptosis after 5[unreadable] Gy of radiation, a reproducible p53-dependent function) and typed these lines for our SNPs providing[unreadable] statistically significant correlations for the impact of a SNP. These cell lines will become a resource for the[unreadable] field that wishes to analyze apoptosis and the p53 pathway. For example SNP 309 in the promoter of the[unreadable] HDM-2 gene, creates a new SP-1 site, increases the levels of HDM-2 protein in a cell, lowers the p53[unreadable] transcriptional response, lowers the apoptotic index and reduces the age of onset of cancers in humans by[unreadable] 12-15 years. We will validate and expand new p53 targets (eg, PTEN, TSC-2, Huntingtin[unreadable] and LINE-1) and determine when and how they are regulated by p53. Collaborative studies with Prives,[unreadable] Lowe and Cordon-Cardo are planned to carry out these aims.